1. Field of the Invention
The present invention relates to safety penetrating instruments for minimally invasive surgical and diagnostic procedures and other procedures in which an anatomical cavity must be penetrated. More particularly, the present invention relates to safety penetrating instruments for use in forming portals for establishing communication with anatomical cavities and body lumens wherein tissue and organ structures are protected from the tips of the penetrating members and to methods of penetrating anatomical cavity walls and body lumens with safety penetrating instruments.
2. Description of the Prior Art
Penetrating instruments are widely used in medical procedures to gain access to anatomical cavities ranging in size from the abdomen to small blood vessels, such as veins and arteries, epidural, pleural and subarachnoid spaces, heart ventricles and spinal and synovial cavities. Use of penetrating instruments has become an extremely popular and important first step in endoscopic, or minimally invasive, surgery to establish an endoscopic portal for a number of procedures, such as laparoscopic procedures in the abdominal cavity. Such penetrating instruments typically include a cannula or portal sleeve and a penetrating member disposed within the cannula and having a sharp tip for penetrating an anatomical cavity wall with the force required to penetrate the cavity wall being dependent upon the type and thickness of the tissue forming the cavity wall. Once the cavity wall is penetrated, the lack of tissue resistance can result in the sharp tip traveling too far into the cavity and injuring adjacent tissue or organ structures. Accordingly, once penetration is achieved, it is desirable to protect the tissue or organ structures in or forming the cavity from inadvertent contact with or injury from the sharp tip of the penetrating member.
Various safety penetrating instruments have been proposed, generally falling into protruding and retracting categories, or combinations of protruding and retracting categories. In protruding safety penetrating instruments, a safety member is spring biased to protrude beyond the tip of the penetrating member in response to the reduced force on the distal end of the safety member upon entry into the anatomical cavity. The safety member can be disposed around the penetrating member in which case the safety member is frequently referred to as a shield, or the safety member can be disposed within the penetrating member in which case the safety member is frequently referred to as a probe. In retracting safety penetrating instruments, the penetrating member is retracted into the cannula upon entry into the anatomical cavity in response to distal movement of a component of the safety penetrating instrument such as the penetrating member, the cannula, a probe or a safety member such as a shield or probe. In safety penetrating instruments that combine elements of the protruding and retracting instruments, typically, the penetrating member of the safety penetrating instrument is retracted and one or more safety members are extended to protrude distally beyond the distal end of the penetrating member. Safety penetrating instruments of the forgoing types are disclosed, for example, in my prior U.S. Pat. Nos. 5,807,402; 5,645,557; 5,645,556; 5,607,439; 5,591,189; 5,584,848; 5,575,804; 5,573,545; 5,571,134; 5,569,289; 5,827,315; 5,810,866; 5,730,755; 5,713,870; 5,707,362; 5,688,286; 5,676,683; 5,676,156; 5,676,682; 5,676,681; 5,665,102; 5,645,076; 5,634,934; 5,681,271; 5,607,396; 5,591,193; 5,191,190; 5,586,991; 5,584,849; 5,573,511; 5,569,288; 5,569,293; 5, 549,564; 5,536,256; 5,478,317; 5,466,224; 5,445,617; 5,431,635; 5,423,770; 5,423,760; 5,401,247; 5,360,405; 5,350,393; 5,336,176; 5,330,432; 5,226,426.
While the protruding, retracting and combination protruding/retracting safety penetrating instruments disclosed in my aforementioned patents have been generally well received, there is still a need in the art for a safety penetrating instrument that is not limited by the disadvantages inherent in such protruding, retracting and protruding/retracting safety penetrating instruments. In protruding instruments, the force required to penetrate the cavity wall necessarily includes the force required to overcome the spring bias on the safety member as well as the resistance of the cavity wall. Insuring that the safety member protrudes after penetration normally requires increasing the spring bias on the safety member and, consequently, the force to penetrate the cavity wall. Retracting safety penetrating instruments have the disadvantages of requiring relatively complex mechanisms to hold the penetrating member in an extended position during penetration and to release the penetrating member for retraction and, concomitantly, not retracting sufficiently quickly and reliably.
Another type of safety penetrating instrument is disclosed in my copending U.S. Pat. No. 5,882,345 filed May 22, 1996, the disclosure of which is incorporated herein by reference. One form of the penetrating member disclosed in that application is made of an absorbent material which, in its dry state, is sufficiently hard to penetrate an anatomical cavity and in its wet or hydrated state becomes soft and pliant so as to avoid injury to internal organs and other tissue in the cavity. While this type of safety penetrating instrument is acceptable in some endoscopic procedures, the possibility of premature hydration and softening of the absorbent material during penetration of the instrument by reason of contact with body fluids limits the effectiveness of this design in many procedures.
It would be desirable, therefore, to provide a safety penetrating instrument that is not limited by the disadvantages of the foregoing types of safety penetrating instruments, but rather provides the necessary protection of tissue and organs by means of a unique, in situ safety shield or sleeve structure.